Fix startup wizard.

Jellyfin.Api/Controllers/StartupController.cs

@@ -95,6 +95,8 @@ namespace Jellyfin.Api.Controllers
         [HttpGet("User")]
         public StartupUserDto GetFirstUser()
         {
+            // TODO: Remove this method when startup wizard no longer requires an existing user.
+            _userManager.Initialize();
             var user = _userManager.Users.First();
             return new StartupUserDto
             {
@@ -115,7 +117,7 @@ namespace Jellyfin.Api.Controllers
 
             user.Username = startupUserDto.Name;
 
-            _userManager.UpdateUser(user);
+            await _userManager.UpdateUserAsync(user).ConfigureAwait(false);
 
             if (!string.IsNullOrEmpty(startupUserDto.Password))
             {

Jellyfin.Server.Implementations/Users/UserManager.cs

@@ -520,6 +520,39 @@ namespace Jellyfin.Server.Implementations.Users
             _defaultPasswordResetProvider = _passwordResetProviders.OfType<DefaultPasswordResetProvider>().First();
         }
 
+        /// <inheritdoc />
+        public void Initialize()
+        {
+            // TODO: Refactor the startup wizard so that it doesn't require a user to already exist.
+            var dbContext = _dbProvider.CreateContext();
+
+            if (dbContext.Users.Any())
+            {
+                return;
+            }
+
+            var defaultName = Environment.UserName;
+            if (string.IsNullOrWhiteSpace(defaultName))
+            {
+                defaultName = "MyJellyfinUser";
+            }
+
+            _logger.LogWarning("No users, creating one with username {UserName}", defaultName);
+
+            if (!IsValidUsername(defaultName))
+            {
+                throw new ArgumentException("Provided username is not valid!", defaultName);
+            }
+
+            var newUser = CreateUser(defaultName);
+            newUser.SetPermission(PermissionKind.IsAdministrator, true);
+            newUser.SetPermission(PermissionKind.EnableContentDeletion, true);
+            newUser.SetPermission(PermissionKind.EnableRemoteControlOfOtherUsers, true);
+
+            dbContext.Users.Add(newUser);
+            dbContext.SaveChanges();
+        }
+
         /// <inheritdoc/>
         public NameIdPair[] GetAuthenticationProviders()
         {

MediaBrowser.Controller/Library/IUserManager.cs

@@ -52,6 +52,11 @@ namespace MediaBrowser.Controller.Library
         /// <value>The users ids.</value>
         IEnumerable<Guid> UsersIds { get; }
 
+        /// <summary>
+        /// Initializes the user manager and ensures that a user exists.
+        /// </summary>
+        void Initialize();
+
         /// <summary>
         /// Gets a user by Id.
         /// </summary>